Add Base64 support for a custom padding byte (like Base32)

Author: garydgregory

src/changes/changes.xml

@@ -48,7 +48,8 @@ The <action> type attribute can be add,update,fix,remove.
       <action type="add" dev="ggregory" due-to="Gary Gregory">Add override org.apache.commons.codec.language.bm.Rule.PhonemeExpr.size().</action>
       <action type="add" dev="ggregory" due-to="Chris Kocel, Gary Gregory">Add support for Base64 custom alphabets #266.</action>
       <action type="add" dev="ggregory" due-to="Gary Gregory">Add Base64.Builder (allows custom alphabets).</action> 
-      <action type="add" dev="ggregory" due-to="Gary Gregory">Add Base32.Builder (allows custom alphabets).</action> 
+      <action type="add" dev="ggregory" due-to="Gary Gregory">Add Base32.Builder (allows custom alphabets).</action>
+      <action type="add" dev="ggregory" due-to="Gary Gregory">Add Base64 support for a custom padding byte (like Base32).</action> 
       <!-- FIX -->
       <action type="fix" dev="ggregory" due-to="Gary Gregory">Optimize memory allocation in PhoneticEngine.</action>
       <action type="fix" dev="ggregory" due-to="Gary Gregory">BCodec and QCodec encode() methods throw UnsupportedCharsetException instead of EncoderException.</action>

src/main/java/org/apache/commons/codec/binary/Base64.java

@@ -72,7 +72,7 @@ public Builder() {
 
         @Override
         public Base64 get() {
-            return new Base64(getLineLength(), getLineSeparator(), getEncodeTable(), getDecodingPolicy());
+            return new Base64(getLineLength(), getLineSeparator(), getPadding(), getEncodeTable(), getDecodingPolicy());
         }
 
         /**
@@ -597,7 +597,7 @@ public Base64(final int lineLength, final byte[] lineSeparator) {
      * @since 1.4
      */
     public Base64(final int lineLength, final byte[] lineSeparator, final boolean urlSafe) {
-        this(lineLength, lineSeparator, toUrlSafeEncodeTable(urlSafe), DECODING_POLICY_DEFAULT);
+        this(lineLength, lineSeparator, PAD_DEFAULT, toUrlSafeEncodeTable(urlSafe), DECODING_POLICY_DEFAULT);
     }
 
     /**
@@ -628,9 +628,8 @@ public Base64(final int lineLength, final byte[] lineSeparator, final boolean ur
      *             Thrown when the {@code lineSeparator} contains Base64 characters.
      * @since 1.15
      */
-    public Base64(final int lineLength, final byte[] lineSeparator, final boolean urlSafe,
-                  final CodecPolicy decodingPolicy) {
-        this(lineLength, lineSeparator, toUrlSafeEncodeTable(urlSafe), decodingPolicy);
+    public Base64(final int lineLength, final byte[] lineSeparator, final boolean urlSafe, final CodecPolicy decodingPolicy) {
+        this(lineLength, lineSeparator, PAD_DEFAULT, toUrlSafeEncodeTable(urlSafe), decodingPolicy);
     }
 
     /**
@@ -652,14 +651,15 @@ public Base64(final int lineLength, final byte[] lineSeparator, final boolean ur
      *            decoding.
      * @param lineSeparator
      *            Each line of encoded data will end with this sequence of bytes.
+     * @param padding padding byte.
      * @param encodeTable
      *            The manual encodeTable - a byte array of 64 chars.
      * @param decodingPolicy The decoding policy.
      * @throws IllegalArgumentException
      *             Thrown when the {@code lineSeparator} contains Base64 characters.
      */
-    private Base64(final int lineLength, final byte[] lineSeparator, final byte[] encodeTable, final CodecPolicy decodingPolicy) {
-        super(BYTES_PER_UNENCODED_BLOCK, BYTES_PER_ENCODED_BLOCK, lineLength, toLength(lineSeparator), PAD_DEFAULT, decodingPolicy);
+    private Base64(final int lineLength, final byte[] lineSeparator, final byte padding, final byte[] encodeTable, final CodecPolicy decodingPolicy) {
+        super(BYTES_PER_UNENCODED_BLOCK, BYTES_PER_ENCODED_BLOCK, lineLength, toLength(lineSeparator), padding, decodingPolicy);
         this.encodeTable = Objects.requireNonNull(encodeTable, "encodeTable");
         if (encodeTable == STANDARD_ENCODE_TABLE || encodeTable == URL_SAFE_ENCODE_TABLE) {
             decodeTable = DECODE_TABLE;

src/test/java/org/apache/commons/codec/binary/Base64Test.java

@@ -242,6 +242,20 @@ public void testBuilderLineAttributes() {
         assertEquals("Zm94\r\n", Base64.builder().setLineLength(4).get().encodeToString("fox".getBytes(CHARSET_UTF8)));
     }
 
+    @Test
+    public void testBuilderPadingByte() {
+        assertNull(Base64.builder().get().getLineSeparator());
+        assertNull(Base64.builder().setLineSeparator(BaseNCodec.CHUNK_SEPARATOR).get().getLineSeparator());
+        assertArrayEquals(BaseNCodec.CHUNK_SEPARATOR, Base64.builder().setLineLength(4).setLineSeparator(BaseNCodec.CHUNK_SEPARATOR).get().getLineSeparator());
+        assertArrayEquals(BaseNCodec.CHUNK_SEPARATOR, Base64.builder().setLineLength(4).setLineSeparator(null).get().getLineSeparator());
+        assertArrayEquals(BaseNCodec.CHUNK_SEPARATOR, Base64.builder().setLineLength(10).setLineSeparator(null).get().getLineSeparator());
+        assertNull(Base64.builder().setLineLength(-1).setLineSeparator(null).get().getLineSeparator());
+        assertNull(Base64.builder().setLineLength(0).setLineSeparator(null).get().getLineSeparator());
+        assertArrayEquals(new byte[] { 1 }, Base64.builder().setLineLength(4).setLineSeparator((byte) 1).get().getLineSeparator());
+        assertEquals("VGhlIGJyb3duIGZveA==", Base64.builder().get().encodeToString("The brown fox".getBytes(CHARSET_UTF8)));
+        assertEquals("VGhlIGJyb3duIGZveA__", Base64.builder().setPadding((byte) '_').get().encodeToString("The brown fox".getBytes(CHARSET_UTF8)));
+    }
+
     @Test
     public void testBuilderUrlSafe() {
         assertFalse(Base64.builder().get().isUrlSafe());